Water boilers Slim

Isotemp SLIM Stainless Steel Marine Water Heaters


The Isotemp SLIM line of Stainless Steel Marine Water Heaters comes with brushed stainless steel cover as well as innovative internal design. The Slim models are characterized by a smaller diameter (12 inches) and longer length.

Isotemp SLIM Stainless Steel Marine Water Heaters are specifically designed for use in the demanding marine environment.  Isotemp SLIM features a brushed stainless steel cover and a 316-grade stainless steel inner tank that is backed by a 5-year limited warranty against leakage due to corrosion or manufacturing defect.

Isotemp Stainless Steel Water Heaters achieve the highest capacity by optimizing the position of the engine water heat exchanger as well as the electrical immersion heater. These are positioned in the lowest part of the tank where the water is coldest in order to ensure an equal heating of all the water in the tank. The water inlets and outlets are specially designed to minimize the mixture of cold and hot water.

All Isotemp tanks come standard with the innovative Isotemp Temperature Control Safety Mixing Valve which protects users from scalding hot water.  Water heated with engine heat exchangers can be heated to 190 degrees or more which can scald those unfamiliar with boat water heaters.  Water will also be heated to 160+ degrees with just the electric heating element alone. By adjusting the valve, the Isotemp thermostat-controlled mixing valve mixes the boat’s water with the hot water to deliver the temperature you want at the faucet. This mixing action also speeds recovery time and extends the volume of hot water you get from a smaller tank.

Following are part numbers and descriptions:

601521S000003 Waterheater Slim 15L, 4 gallon 115V/750W with mixing valve
601531S000003 Waterheater Slim 15L, 4 gallon 230V/750W with mixing valve
602021S000003 Waterheater Slim 20L, 5.3 gallon 115V/750W with mixing valve
602031S000003 Waterheater Slim 20L, 5.3 gallon 230V/750W with mixing valve
602521S000003 Waterheater Slim 25L, 6.5 gallon 115V/750W with mixing valve
602531S000003 Waterheater Slim 25L, 6.5 gallon 230V/750W with mixing valve

My advantages

  • Extra long, corrugated coils for high heat exchange efficiency
  • Special 7.0 bar / 100 psi safety valve
  • Simple winter drain
  • Ultra-thick insulation for lowest temperature loss
  • Electrical plug and play immersion heating element, especially designed to heat also the water at the bottom of the tank
  • Thermostat mixing valve protects against scalding and delivers consistent temperatures at the faucet
  • Standard 750 watt immersion heating element heats water quickly but will not overload generators or dock breakers
  • Robust design
  • Water tank in 316 grade stainless steel
  • External cylinder in stainless steel
  • Stable fixing feet in stainless steel
  • Horizontal deck or bulkhead mounting
  • Vertical bulkhead mounting (valves down)

Technical details overview

Slim 15
Slim 20
Slim 25
Part number
Volume (gal.)
Dimensions L x ø D* (inch)
20 x 12
25 x 12
30 x 12
Weight (lbs)

* Including thermostat mixing valve

Dimensional Drawing Slim (click here) (PDF, 34 kB)



Product images